The proposed research will seek to elucidate some aspects of the biosynthesis of vitamin B12 (B12 biosynthesis) and of the metabolism of related compounds. Vitamin B12 is the most recently discovered vitamin, and by far the most complex. Although the molecule shows structural similarities to porphyrins, there are extensive differences from porphyrins and numerous unique additional features. The mode of formation of many of the structural components of B12 remains unknown. It is proposed to study: (1) the formation of delta-aminolevulinic acid, the precursor of the tetrapyrrole structure, using plants and bacteria; (b) the enzymology of the amidation of the carboxylic acid side chains of corrinoids. The proposed topics entail the growth of plants and of B12-producing bacteria, and the study of various enzymes and enzyme systems. The approaches will require paper chromatography and paper electrophoresis, high pressure liquid chromatography, conventional column chromatography, spectrophotometry, and the determination of radioisotopes.